The basis of the strategy currently used to design multiple electric circuit devices is the use of a rigid metallic base with a high electric conductivity (generally made with copper or copper alloys). Until now, the need for a rigid metal base with a high temperature of elimination of the stress generated by cold deformation, thus maintaining its mechanical properties when heated by the current passing through, has forced the use of alloys with conductivities lower than that of high purity copper (normally between 35 and 70% IACS for strain strengths between 700 and 500 MPa, whereas high purity electrolytical copper generally presents strain strengths of 380 MPa and conductivities of 101% IACS).
The electric conductivity of commonly used alloys inevitably decreases as a high strain strength is needed.
The alloys that constitute the metal base are selected from a compositional series of binary and ternary alloys with an electric conductivity that decreases as their mechanical properties improve. For example, a copper/iron alloy often used for these functions presents an electric conductivity of 60% IACS and a strain strength of 550 MPa.